The present invention relates to a method of producing a blood type checking reagent containing a lectin. The blood type checking reagent exhibits specific cohesion relative to H-antigen on a red blood cell membrane or an erythrocyte membrane. Accordingly, it is possible to accurately and quickly determine a blood type even from a small bloodstain.
In general, lectin extracted from a plant includes anti-A1 lectin (from Dolicos biflorus) and anti-H lectin (from Ulex europaeus). The anti-H lectin extracted from Ulex europaeus has been used for, for example, determining a blood type. Anti-H lectin with improved activity is called H-antigen lectin strong, and suitable for checking a blood type of a trace amount of body fluid and a hair (dissociation test). The anti-H lectin strong has agglutinin tilter four times larger than that of conventional anti-H lectin. Accordingly, it is possible to determine a blood type of a small amount of sample (refer to Non-patent Reference 1 and Non-patent Reference 2). The following table shows comparison of agglutinin tilter between the anti-H lectin strong and the conventional anti-H lectin.
Agglutinin tilter*Anti-H lectin26 (64) Anti-H lectin strong28 (256)*Measured with continuous dilution method (2% O-type human erythrocyte agglutinin tilter PBS)
Further, lectin may be extracted from animal such as loach, especially from an egg thereof. The lectin extracted from loach has a molecular weight of 15,000 to 50,000, and is used for determining a blood type (refer to Patent Reference 1).    Non-patent Reference 1: Japanese Society of Laboratory Medicine Library XII (1996)    Non-patent Reference 2: Product Report No. 105 (Seikagaku Corporation)    Patent Reference 1: Japanese Patent Publication No. 11-083862
The conventional method of checking a blood type has the following disadvantages. First, it is difficult to determine a blood type sampled from a bloodstain (dissociation test) using the anti-H lectin extracted from Ulex europaeus. Second, it is difficult to obtain raw materials for producing the blood type checking reagent using the conventional anti-H lectin. Further, it is necessary to use a large amount of raw materials, thereby increasing cost. Third, the agglutinin tilter of the lectin extracted from Ulex europaeus largely depends on a raw material (seed), and it is difficult to obtain constant agglutinin tilter within lot. Fourth, it is difficult to detect H-antigen using the lectin extracted from loach.
In view of the problems described above, an object of the present invention is to provide lectin for checking a blood type and a blood type checking reagent containing the lectin, in which it is possible to accurately and quickly determine a blood type even from a small bloodstain. Another object of the present invention is to provide a method of checking a blood type using the blood type checking reagent containing the lectin.
Further objects and advantages of the invention will be apparent from the following description of the invention.